Final answer:
Pubertal delay in girls is typically considered if breast development has not occurred by age 13. This milestone is part of the broader changes during puberty, including menarche, which generally occur around 12-13 years old.
Step-by-step explanation:
The pubertal delay in girls is a concern if breast development has not occurred by the age of 13 years. While breast development typically begins between the ages of 9 and 11, a notable pubertal milestone, girls may sometimes start a bit later. Although variability in the onset of puberty is common due to factors such as genetics, nutrition, and environment, medical guidelines suggest that an investigation may be warranted if there are no signs of puberty, such as breast development, by the age of 13.
Puberty in girls encompasses several changes, including the onset of menstruation (menarche), usually around 12-13 years old, which follows breast development by about two years. Early or late onset of puberty can be a source of concern and self-consciousness for young individuals, but often remains within normal variations.